Over 50s do just as well on HIV treatment, but more likely to be diagnosed late and to change treatment sooner

Michael Carter
Published: 10 August 2007

Older HIV-positive patients are just as likely as younger HIV-positive individuals to experience good increases in their CD4 cell count and achieve adequate falls in their viral load after starting potent antiretroviral therapy, French investigators report in the September 1st edition of Clinical Infectious Diseases. T

The investigators did, however, find that older patients (defined as the over-50s) were more likely to have their HIV diagnosed late, and late diagnosis was a factor associated with a poorer immunological and virological response to anti-HIV treatment. Furthermore, the study revealed that the over-50s were more likely to change their antiretroviral therapy because of side-effects than younger patients.

HIV specialists are encountering an increasing number of older patients. This is because successful anti-HIV treatment is meaning the many individuals with chronic HIV infection are surviving in older age, and because more over 50s are being diagnosed with HIV.

Late diagnosis of HIV is common amongst older patients for a number of reasons. Older patients may not think of themselves as being at risk of HIV; doctors are less likely to recommend an HIV test to older individuals with symptoms suggestive of HIV infection; and routine testing is uncommon in older patients.

There is controversy about the immunological and virological efficacy of antiretroviral therapy in patients aged over 50. French researchers noted that studies reporting a poorer outcome in antiretroviral-treated older patients failed to take into account the likelihood of late diagnosis in this population. They hypothesised that if this was taken into account, older and younger patients would have a comparable response to anti-HIV treatment.

To test this theory, investigators designed a retrospective study involving 639 patients who commenced potent antiretroviral therapy in Toulouse between 1996 and 2006. They categorised patients as being older if they were aged 50 or above (99 individuals).

They then compared immunological, clinical, and virological responses to HIV treatment in older and younger patients. An immunological response was defined as a CD4 cell count above 350 cells/mm3 after six months of anti-HIV treatment. A clinical response was the absence of new AIDS-defining illness or death at six months. A virological response was defined as a viral load below 200 copies/ml after six months of therapy.

The investigators also compared the number of younger and older patients who needed to change treatment because of side-effects.

Finally, data were collected on late-diagnosis – defined as a CD4 cell count below 200 cells/mm3 or the presence of an AIDS-defining illness at the time of diagnosis to see if this affected treatment outcomes.

After six months of potent anti-HIV treatment, median CD4 cell count increased by 100 cells/mm3 in older patients and 104 cells/mm3 in younger patients. The difference was not statistically significant. A comparable proportion of older (55%) and younger (51%) patients had an immunological response to HIV therapy - CD4 cell count above 350 cells/mm3 - at this point in time.

The investigators also found that similar proportions of older (67%) and younger (69%) patients had a virological response – a viral load below 200 copies/ml - after six months of antiretroviral treatment.

Similar numbers of patients (8%, older versus 6%, younger, a non-significant difference) experienced clinical progression of their HIV disease.

Although just over two thirds of older and younger patients stopped taking their first antiretroviral regimen, the investigators found that older patients did so significantly earlier than younger patients (median six months, versus 14 months, p < 0.01).

Researchers also found that older patients were significantly more likely to discontinue their first regimen because of side-effects (odds ratio: 2.0). Furthermore, the over-50s were more likely than younger patients to stop taking their first combination because of neuro-psychiatric side-effects (9% versus 3%, p = 0.03) and because of blood disorders (14% versus 6%, p = 0.03).

As regards late diagnosis, the investigators found that significantly more of the older patients (56%) than under-50s (45%, p = 0.05) received their HIV diagnosis when their CD4 cell count was already below 200 cells/mm3 or when they were already ill with an AIDS-defining illness.

They also found that significantly fewer individuals with late diagnosis had an immunological response to HIV treatment (19% versus 75%, p < 0.001), and that individuals diagnosed late were significantly more likely to have experienced clinical progression during the first six months of HIV therapy (odds ratio: 3.4).

“After six months of highly active antiretroviral therapy (HAART), immunological and virological evolution did not differ between [older and younger] patients”, comment the investigators. They add, “late testing was more frequent amongst the older group and was significantly associated with less frequent immunological reconstitution and with clinical progression.”

The investigators conclude, “earlier diagnosis of HIV infection is mandatory for older patients, because the use of HAART allows them to achieve immunovirological responses similar to those in younger patients.”

Reference

Cuzin L et al. Immunological and clinical responses to highly active antiretroviral therapy in patients with HIV infection aged > 50 years. Clin Infect Dis, 45: 654 – 657, 2007.